Implementation:CARLA simulator Carla Commands API Spec

Knowledge Sources	CARLA
Domains	Simulation, Autonomous Driving, API Specification
Last Updated	2026-02-15 05:00 GMT

Overview

YML specification file that defines the command module classes used for batch operations in the CARLA Python API, including SpawnActor, DestroyActor, ApplyVehiclePhysicsControl, ApplyVehicleControl, and Response.

Description

This YML file specifies the command classes under the command module that enable batch execution of simulation operations via client.apply_batch() and client.apply_batch_sync(). The Response class reports success (actor_id) or failure (error string) for each command. SpawnActor spawns actors with a blueprint and transform, optionally attached to a parent, and supports chaining via the then() method. DestroyActor removes actors by ID. ApplyVehiclePhysicsControl and ApplyVehicleControl modify vehicle physics and driving controls respectively. These commands allow efficient batch spawning, destruction, and configuration of many actors in a single simulation step.

Usage

Use these command classes with client.apply_batch() or client.apply_batch_sync() to perform efficient batch operations. This is particularly useful for spawning or destroying many actors at once, such as in traffic generation scripts.

Code Reference

Source Location

Repository: CARLA
File: PythonAPI/docs/commands.yml

Signature

- module_name: command
  classes:
  - class_name: Response
    instance_variables:
    - var_name: actor_id       # type: int
    - var_name: error          # type: str
    methods:
    - def_name: has_error       # return: bool

  - class_name: SpawnActor
    instance_variables:
    - var_name: transform      # type: carla.Transform
    - var_name: parent_id      # type: int
    methods:
    - def_name: __init__(blueprint, transform)
    - def_name: __init__(blueprint, transform, parent)
    - def_name: then(command)

  - class_name: DestroyActor
    instance_variables:
    - var_name: actor_id       # type: int

  - class_name: ApplyVehiclePhysicsControl
    instance_variables:
    - var_name: actor_id           # type: int
    - var_name: physics_control    # type: carla.VehiclePhysicsControl

  - class_name: ApplyVehicleControl

Import

import carla
SpawnActor = carla.command.SpawnActor
DestroyActor = carla.command.DestroyActor

I/O Contract

Class	Input	Output	Description
SpawnActor	blueprint, transform, [parent]	actor_id via Response	Spawns an actor into the simulation
DestroyActor	actor or actor_id	bool via Response	Destroys an actor
ApplyVehiclePhysicsControl	actor, physics_control	None	Applies physics parameters to vehicle
ApplyVehicleControl	actor, control	None	Applies driving controls to vehicle
Response	N/A	actor_id or error	Result of a batch command execution

Usage Examples

import carla

client = carla.Client('localhost', 2000)
world = client.get_world()
bp_lib = world.get_blueprint_library()
spawn_points = world.get_map().get_spawn_points()

# Batch spawn with autopilot chaining
SpawnActor = carla.command.SpawnActor
SetAutopilot = carla.command.SetAutopilot
FutureActor = carla.command.FutureActor

batch = []
for i, sp in enumerate(spawn_points[:10]):
    bp = bp_lib.filter('vehicle.*')[i % len(bp_lib.filter('vehicle.*'))]
    batch.append(SpawnActor(bp, sp).then(SetAutopilot(FutureActor, True)))

results = client.apply_batch_sync(batch, True)
vehicles = [r.actor_id for r in results if not r.has_error()]

# Batch destroy
batch = [carla.command.DestroyActor(v) for v in vehicles]
client.apply_batch_sync(batch)

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